Directional drilling in the early stages of petroleum drilling development was practiced in unusual situations and only those skilled in that particular art were in control of drilling operations for the directional controlling activity. As the drilling art became more professional, and more technical support developed, the trend was toward more complex and responsive down hole drilling apparatus to reduce the skill requirements on the drilling floor. Additionally, well bore survey equipment improved and measurement while drilling became practical. The driller could determine what was taking place down hole every few feet and less risk was involved in making drilling technique decisions. Simple actions on the part of the driller could dictate configuration of the down hole apparatus and effective down link command became a reality. The thrust of current development is directed to making the responsive down hole directional drilling control apparatus more simple and economical to build and maintain.
It is therefore an object of this invention to provide apparatus to be used with a down hole motor, responsive to manipulations of the surface drilling controls, to change the down hole assembly between the straight drilling configuration and the directional drilling configuration.
It is another object of this invention to provide apparatus that can be attached to, or be made part of, the drilling motor housing to accomplish the configuration change within, the motor body.
It is yet another object to provide means to respond to selective surface drilling fluid flow controls to disable the deflection means to enable drilling with the sub in the straight configuration.
It is still a further object of this invention to provide a combination of means for responding to down link commands produced by exercise of surface mud pump controls to control down hole configuration change to enable a combination of deflection subs to be used independently in a down hole drilling assembly.
It is still another object of this invention to provide apparatus to respond to brief intervals of reverse mud circulation to manipulate the deflection controls down hole.
It is still a further object to provide a signal valve responsive to the change in configuration of the sub to produce a drilling fluid pressure pulse detectable at the surface to indicate that configuration change is taking place down hole.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.